This invention relates to a floating conveyor system, and more particularly, to a system for transporting sand and gravel from a floating dredge to a land based station.
Floating conveyor systems are useful to transport sand and gravel from a floating dredge or winning machine across a body of water to a land based station such as a raw gravel pile or gravel processing site. Examples of winning machines or dredges include clam shell dredges, bucket ladder dredges, and the like.
Currently, floating conveyor systems include multiple conveyor units which are coupled together to form an extended floating conveyor system for bridging the body of water and transporting the sand, gravel or other dredged material. These current systems require one end of each conveyor unit to be supported on a float assembly consisting of typically six or eight individual pontoons. The float end of each conveyor unit includes a ball bearing slewing ring beneath which is positioned one end of the conveyor for transferring the material. The ball bearing slewing ring is essentially an enlarged annular conduit having a bearing ring at an upper edge thereof. The bearing ring is designed to support the trailing end of an adjacent conveyor unit coupled thereto. The leading and trailing ends of adjacent conveyor units are coupled so that the trailing end of one conveyor unit is supported upon the bearing ring at the leading end of an adjacent conveyor unit. The sand and gravel travels on the conveyor unit upwardly toward the trailing end of the conveyor unit and then is deposited off of the trailing end of the conveyor down through the ball bearing slewing ring of the next unit and onto the leading end of the conveyor and is then transported upwardly toward the trailing end of that unit. Each conveyor unit only has floats at the leading end of the unit underneath the ball bearing slewing ring,
This prior embodiment of a floating conveyor system has numerous disadvantages. Floating conveyor systems of this type must have catwalks and connection ways for personnel to travel along the conveyor system between the dredge and the land based station. The individual conveyor units in the prior art system are configured so that the trailing end of a conveyor pivots atop the bearing ring on the adjacent conveyor unit, The slewing motion or pivoting of the conveyor units at their intersections presents significant hazards for personnel walking from one unit to the next so that current floating conveyor systems do not provide an adequately safe walking area, connecting way, or catwalk. Furthermore, the catwalks must conform with safety and governmental regulations.
Another problem associated with floating conveyor systems as previously described is that the trailing end of each arriving belt must be placed on the float assembly at the leading end of the adjacent unit with the sand and gravel being transferred from one to the other through the ball bearing slewing ring structure. This arrangement creates a high profile and unstable configuration such that loads upon the conveyor system due to wind forces or wave motions create shear forces on the slewing ring. The juncture between adjacent conveyor units at the slewing ring is not adapted to withstand twisting, torsional or shear forces. As a result, such forces may cause the system to snap apart or collapse.
Another considerable disadvantage with prior systems is that the system can only be lengthened or shortened at great expense with considerable time and effort. All of the conveyor units along with the floating dredge must be pulled ashore and the conveyor belts removed with a suitable crane in order to add or remove a conveyor unit. Typically, this task can only be performed during clement weather conditions and is still very time consuming and costly.
A further disadvantage of prior systems is the tendency for the conveyor to clog and become overloaded. The sand and gravel is transferred from one unit to the next through a restricted orifice on the slewing ring. Often larger rocks and dredged material become jammed and clogged while passing through the slewing ring. In addition to the obvious problem of interrupting the flow of material on the system and the requirement of unclogging the blockage, the added weight on the slewing ring platform produces a risk of capsizing the floating equipment.